Mud, iron or other mineral settleable solids in boiler feedwater cause a multitude of problems within boilers, connecting pipes and control valves. Such solids precipitate a scaly deposit on the interior surface of boiler tubes reducing heat transfer coefficients of the tubes for absorbing heat from furnace gases and producing steam which increases the amount of fuel burned to obtain a desired boiler power output. In order to offset this decrease in boiler efficiency, frequent teardowns must be made during which the tubes of the boiler are reamed of this scale until the bare metal is exposed. Soluble chemicals are introduced into the feedwater to inhibit precipitation of these solids and to neutralize the solution adding to the cost of the operation and cutting down on the life of the boiler. The settleable solids system is similar to that of my industrial cleansing apparatus covered by U.S. Pat. No. 4,144,172.
In boilers with 20% to 100% make-up water, chemicals are usually premixed in a separate vessel and pumped into the condensate return tank. The premixing is not always complete in the process and grit therefrom can cause undue wear in the feedwater pump and clog up the piping in general. Also, cold feedwater entering a hot boiler thermally shocks the hot feedwater in the boiler and reduces solubility thereby adding to the scaly deposit problem.
There is an established need for a solids separator which uniformly preheats and chemically treats boiler feedwater as it cleans the same, requiring only the occasional opening of a valve at the bottom of a settling tank for flushing out the solids therein.